Riesch, whose younger sibling skied out of the closing slalom after ending the first run on the cusp of a medal in fourth place, consoled a tearful Susanne at the finish.
"I was careful not to celebrate too much because I knew how disappointed my sister was," the winner said waiting in the swirling snow.
"She was crying and it hurt me. But she is young and will get more chances to win medals," added Riesch, who has now outgunned much-hyped American Lindsey Vonn as Alpine skiing's golden girl.
A gifted all-rounder, Riesch could pointed out that she had done better than Vonn, who straddled a gate in the first run and will leave the Games with just two medals, gold in the downhill and bronze for Super-G.
"This is not the way I look at it," Riesch said when asked how if felt to have eclipsed the American speed queen, her closest friend and greatest rival on the circuit.
"It is difficult for us all-rounders because we are expected to win plenty of medals but Lindsey has a gold and a bronze and, given the circumstances with her injuries and everything, I'm sure she is happy to have done that," she added.
Riesch earned Germany's women their third Alpine skiing gold medal of the Games, with Viktoria Rebensburg winning the giant slalom, and their best overall Olympic result since Katja Seizinger and Hilde Gerg took three titles at the 1998 Games.
Riesch senior had led after the first run and beat Austrian Marlies Schild, slalom bronze medallist in Turin four years ago as well as second in the 2006 combined, into second place by 0.43 seconds with a total time of one minute 42.89.
Not so long ago Schild would have been unhappy with anything other than a gold medal. However, the Austrian was certainly not complaining after taking silver.
The 28-year-old, the world's best slalom racer with two World Cup titles in that event, has taken over a year to recover from a bad leg fracture sustained in a pre-season crash in 2008.
She needed surgery four times, missed the entire 2008-09 season and returned to the World Cup circuit only in November to post victories in Flachau and Lienz, bringing her World Cup tally to 22 wins, 20 of them in slalom.
"I could not ski for 11 months and I didn't know six months ago if I would be able to ski fast enough to win again," she said.
"I have two medals at home and this is my third so I am very happy with that."
A former all-rounder, Schild now focuses solely on the slalom, to reduce the risk of another injury.
That leaves her more time to cheer her boyfriend, Olympic slalom champion Benjamin Raich, who will be among the favourites in the closing skiing event at Whistler, the men's slalom on Saturday.
"I really hope he wins," she said. "Then the Olympics would be absolutely perfect for me."
Sarka Zahrobska of the Czech Republic took the bronze medal in the final race of the women's programme at Whistler Creekside. It was her country's first medal in Alpine since Olga Charvatova was third in downhill for the former Czechoslovakia in 1984.
Zahrobska's agonising decision to split from her father and appoint her boyfriend as her coach paid off.
"I am overjoyed," Zahrobska said. "I have worked really hard for this so I am certainly going to be celebrating tonight."
Zahrobska has long been among the world's top woman skiers, winning slalom medals at each of the past three world championships, including gold in Sweden in 2007.
She was coached from childhood by her father Petr but decided to part ways with him last year and credited her Olympic success to her new team.
"We are really a small team, I have only three people, I have my serviceman, I have my physiotherapist and my coach," she said.
"Sometimes it's very hard to train with a small team but we co-operate very well."
Defending champion Anja Paerson missed a gate in the second leg and the Swede, who had a big crash in the downhill but came back to win bronze in the super combined, said she would now see doctors to see whether she would see out the World Cup season.
"After that I will take a big break and decide (whether) to keep on going," added the winner of a record-equalling six Olympic medals.
"If not, in two weeks you will see the last race from me."
Place of birth: Garmisch-Partenkirchen, Germany
No previous Olympic results:
Career achievements: Gold medallist, 2009 World Championships, slalom
Champion, 2008/09 World Cup, slalom
Champion, 2007/08 World Cup, super-G
Champion, 2007/08 World Cup, super combined
Runner-up, 2008/09 World Cup, overall
2x Third place, 2007/08, 2003/04 World Cup, overall
This season's World Cup slalom leader, Riesch, won her first Olympic gold at her debut Games in Vancouver.
She started skiing at the age of three and was also a nationally ranked tennis player. Her sister Susanna is also a member of the German Alpine skiing team.
The German is close friends with American all-rounder and Alpine skiing rival Lindsey Vonn and the pair often spend Christmas together with Riesch's family.
The 25-year-old ruptured knee ligaments in 2004 and missed the remainder of the 2003/2004 season. She also missed part of the following season after dislocating her shoulder.
She missed out on the 2006 Winter
Riesch then injured knee ligaments again in training before the 2009 World Championships. She recovered to win the world title.